Method of manufacturing dies



y 21, 1964 SCHULTINK ETAL 3,141,357

METHOD OF MANUFACTURING DIES Filed March 9, 1961 INVENTORS LUBERT US 5C HUL'I'INK ABRAHAM J.VAN DER WAGT.

M f AG ENS United States Patent signors to North American Philips Company, Inc., New

York, N.Y., a corporation of Delaware Filed Mar. 9, 1961, Ser. No. 94,635 Claims priority, application Netherlands Mar. 12, 1960 8 Claims. (Cl. 76-107) It is known to surround drilled diamonds intended for drawing metal wires by cast iron preferably containing silicon and to fasten the diamond thus enveloped in a setting. Although this method of setting yields satisfactory results there is a need for a method of manufacturing a die in which the diamond can be fastened in a cheaper manner in the setting and in which the diamond is heated prior to the enveloping process, thus oxidation of the cast iron is minimized. It is furthermore desirable that the process should be performed more rapidly than previously accomplished. These requirements are fulfilled by the method according to the invention in which the diamond provided with a bore is arranged in a cylindrical space provided in the setting and which has a larger inner diameter than the outer, diameter of the diamond in a plane at right angles to the bore, the bottom boundary of the said space being provided with a central aperture. Then a ring of a metal having a lower melting point than the setting is arranged around the diamond in the space; the said metal being, more-.

over, capable of wetting the diamond and of adhering to the setting material. The volume of the ring is chosen so that the molten and subsequently solidified metal of the ring fills out the space; then the setting is introduced into the concentrator of a high-frequency generator, the ring being melted after the current has been switched on. The current is then switched off and after the setting has solidified and has been removed from the concentrator the solid metal mass is provided with an opening corresponding with the bore of the diamond. In this case the temperature of the cast iron may be lower than in the known method, since losses of heat are avoided during the transport of the crucible and during the casting process.

In order to avoid oxidation of the molten meta the setting and the diamond are arranged, in accordance with a further aspect of the invention, in a gastight space having a passage for a slidable tube or rod to which the ring is fastened in a readily detachable manner and which has a centering tube or pin for the diamond. Prior to melting of the ring, this space is filled with a non-oxidizing gas, the bottom of this space being formed by the concentrator which is provided with a chamber to accommodate the setting.

According to a further embodiment of the invention further improved protection of the molten cast iron from oxidation is obtained by constructing the ring from two parts, of which the lower part is preferably made of silicon-containing cast iron having a silicon content of about 3% and the upper, much smaller part, serving as a cover, is made from a non-corrosive metal alloy of which the melting point is lower than that of material of the lower part. The concentrator and the location of the setting in this concentrator is chosen so that only the lower part of the ring lies in the high-frequency field and melts, when the current is switched on. Then the cover ring sinks down into the high-frequency field and is also melted. In a further embodiment of the invention the concentrator is provided with a central opening, with which an exhaust duct is connected prior to switching-on of the current. This facilitates enveloping of the diamond by the iron and the molten iron flows more smoothly around the diamond.

Since it may occur that, owing to the good wetting of the setting, the molten metal of the ring flows over and across the upper edge, the setting is provided, in accordance with a further aspect of the invention, with an upright edge which is preferably coaxial to the chamber and which is removed from the ring after solidification and cooling.

In a preferred embodiment of the invention the setting is made of a substantially chromium-free metal, since it has been found that chromium of the setting rapidly diffuses into the molten cast iron and thus forms a very hard crust. Good results have been obtained with a setting consisting of an iron-nickel-cobalt alloy having approximately 28% of nickel and about 18% of cobalt. The setting may also be made from a metal known under the trademark of Monel consisting of about 70% of nickel and 30% of copper.

In one embodiment of the invention the cover ring is made from a nickel-manganese alloy consisting of about 60% of nickel and 40% of manganese.

In accordance with the invention a device for carrying out the method described above for the manufacture of a die formed by a bored setting and a bored diamond fixed therein is characterized in that it preferably comprises a glass bell, with which a gas duct can be connected and which is provided with a passage having a stufiing box for a tube or rod and which bears on a plate of refractory material, which is supported by the concentrator of a high-frequency heating system, this concentrator having an annular chamber to accommodate the setting, the concentrator having, moreover, an opening which is coaxial to the chamber and a setting support therein made from refractory material and provided with a channel. The assembly is supported by a plate of refractory material having a channel, which communicates at one end with the channel in the support and which can be connected at the other end with an exhaust duct.

In one embodiment of the invention a metal tube or rod is provided, which is adapted to slide through the stuffing box. The cast iron ring and the cover ring can be fastened in a readily detachable manner to the tube or rod end located in the bell. This end supports, moreover, a readily detachable, coaxially arranged, thin metal tube or rod of small diameter, which projects into the cast iron ring and of which the melting temperature exceeds that of the cast iron.

In a further embodiment of the invention the bottom of the chamber in the setting is provided with a thin, upright rim coaxial to the bore. During the casting process the diamond bears on this edge, so that the molten cast iron may more easily flow around it.

The invention will now be described more fully with reference to a drawing which shows one embodiment of a device according to the invention in a longitudinal sectional view.

In the drawing the reference numeral 1 designates a glass bell, which is provided with a stub 2. The bell has furthermore a stufling box consisting of a metal bottom piece 3 and an annular gland also of metal 4, between which the packing 5 is clamped. The bell is arranged on an asbestos plate 6. This plate lies on a concentrator 7, which is connected to a high-frequency generator. The concentrator 7 has a chamber 8 to accommodate a setting 9 of the metal known under the trademark of Monel of the International Nickel Co., Inc., containing about 70% nickel and about 30% copper. The melting point of the setting amounts to about 1330 C. The setting 9 has a conical bore 10 and is supported from a ceramic tube 11. The concentrator and the tube 11 bear on a supporting plate 12 made from asbestos cement chromium-containing material.

and providedwith a channel 13, which opens out at one end in the centre of the tube 11 and which communicates at the other end with an exhaust duct connection 14. The setting 9 has an upright rim 15 and a chamber 16, formed partly by the body of the setting and partly by the upright rim, where a drilled diamond 17 is arranged on a thin edge 17a. In the chamber 16 is arranged a cast iron ring'18, which has a silicon content of about 3%. On top of the ring 18 is provided a cover ring 19 of a metal alloy of 60% of nickel and 40% of manganese. This alloy is free of oxidation. The volume of the cover ring 19 is much smaller than that of the ring 18; the volumes of the two rings together are approximately equalto the contents of the chamber 16 minus the volume of the diamond 17 and of the chamber portion surrounded by the ring 15. Through the stuffing box in the top of the bell 1 is taken an aluminum tube 20, to which a supporting member 21 is secured. This support 21 is provided with springs 22, which are capable of holding, in a readily detachable manner, the ring 18, shown in broken lines, with the cover ring 19. The support has furthermore a tube 23, into which a thin tube 24 is inserted, of which the outer diameter is so small that it fits in the conical end of thebore in the diamond. This tube is made of nickel.

When the diamond 17 is to be fastened in the setting 9, previously provided with a bore, it is arranged in the chamber. 16 on the rim 17a, after which the setting with the diamond is placed on the tube 11. The bell 1 is then supported provisionally. The tube 20 is lowered until the tube 24 bears on the diamond 17 and arrives at the inlet of the bore. Thus the setting 9, the diamond 17 and the ring 18, shown in broken lines, are relatively centered. Then the ring 18 and the cover ring 19 are lowered in the chamber 16. The bell is then placed on the asbestos plate 6 and at the end 14 is connected an exhaust duct and through the stub 2 a non-oxidizing gas is introduced into the bell. Subsequently, a high-frequency current is passed through the concentrator 7 and, the proportions being suitably chosen, the ring 18 melts in about 90 seconds.

The melting point of the cast iron ring 18 (about 1200 C.) is lower than that of the setting 9, which is about 1330 C. The melting point of the cover ring 19 is again lower than that of thering 18, but this cover ring 19 lies beyond the field of the concentrator 7, so that it does not melt immediately, However, as soon as the ring 18 has melted, the cover ring19 sinks down and also arrives in the field, so that it melts and forms a protective layer on the cast iron, since the material of the cover ring is anon-oxidizing 'metal. After about 100 seconds the whole process is achieved and the current is switched off. After solidification the setting 9 with the clamped tube 24 is taken out of the coil and the edge 15 is milled away. The underlying metal is bored, so that tube 24 is also removed; a conical opening is provided after which the setting 9 is readyfor'use.

In contrast to the known method the cast iron ring 18 is melted in the setting 9, which is ready for use after a simple subsequent treatment. The whole process is carriedout more rapidly. Prior to and during the melting process the diamond is previously heated so that stresses in the diamond are avoided, and the die can be manufactured at lower costs.

The setting is preferably not manufactured from It has been found that chromium diffuses rapidly into the cast iron, which absorbs chromium from the outer side, thus forming a very hard crust. The whole cast iron pellet is likely to be impregnated by chromium. In general, no alloy will be used which is not capable of wetting the diamond during melting. For the setting, use may also be made of an iron-nickel-cbalt alloy, having about 28% of nickel and 18% of cobalt.

The materials of the component parts are preferably chosen so that during the melting process the cast iron forms an alloy with the material of the setting and the cover ring, the latter also forming an alloy with the setting material. The tube 24, which may also be a rod, is made of nickel and its melting temperature must exceed that of the ring 18. The tube20 may furthermore be connected to an exhaust duct. It has been found that the whole process can be carried out by an unskilled staff, in contradistinction to the known method, in which experience and skill play an important part.

What is claimed is:

l. A method of manufacturing a drilled diamond die in a metal setting comprising arranging a drilled dia mond in a gas-tight chamber in said setting, providing a non-oxidizing gas in said chamber, said chamber having a larger inner diameter than the outer diameter of said diamond, providing a bore in said setting opening centrally into said chamber, said chamber having a central aperture adjacent to and aligned with one end of said bore, providing a metal ring in said chamber surrounding said diamond and having a melting point lower than the melting point of said setting, said metal ring being capable of wetting said diamond and adhering to said setting, the molten and subsequently solidifiedmetal of the ring being located in said chamber, introducing the setting into the field of a concentrator of a high frequency generator to melt said ring, and drilling said metal mass after solidification thereof to provide an opening corresponding to the bore of said diamond and at the other end of said bore.

2. A method of manufacturing a drilled diamond die in a metal setting as claimed in claim 1 wherein said concentrator is provided with a vacuum duct.

3. A method of manufacturing a drilled diamond die in a metal setting comprising arranging a drilled diamond in a cylindrical chamber in said setting, said chamber having a largerinner diameter than the outer diameter of said diamond providing a bore in said setting, said chamber having a central opening adjacent to said bore, providing a metal ring consisting of two portions, the lower portion being a silicon-containing cast iron and an upper portion of a non-corrosive metal alloy having a melting point lower than the melting point of the lower portion, and both said portions having a melting point lower than the melting point of said setting, said metal ring being capable of wetting said diamond and adhering to said setting, and the volume thereof being chosen so that the molten and, subsequently solidified metal of the ring substantially fills out said chamber, introducing the setting into the field of a concentrator of high frequency generator to melt said lower portion of the ring first and to melt the upper portion after said upper portion of the ring descends into the heating zone, and drilling said metal mass after solidification thereof to provide an opening corresponding to the bore of said diamond. 4. A method of manufacturing a drilled diamond die in a metal setting as claimed in claim 3 wherein said upper portion of the metal ring is made from a nickelmanganese alloy having about 60% of nickel and 40% of manganese.

5. A methodof manufacturing a drilled diamond die in a metal setting comprising providing said setting with an upright rim, arranging a drilled diamond in a gas-tight cylindrical chamber in said setting, said upright rim being arranged co-axial with said chamber, said chamber having a larger inner diameter than the outer diamter of said diamond, providing a bore in said setting opening centrally into said chamber, said chamber having a central aperture adjacent to one end of said bore, providing a metal ring in said chamber surrounding said diamond and having a melting point lower than the melting point of said setting, said metal ring being capable of wetting said diamond and adhering to said setting, the molten and subsequently solidified metal of the ring being located in said chamber, providing a non-oxidizing gas in said chamber, introducing the setting into the field of a concentrator of a high frequency generator to melt said ring, and drilling said metal mass after solidification thereof to provide an opening corresponding to the bore of said diamond an removing said edge after solidification and cooling of said ring.

6. A method of manufacturing a drilled diamond die in a metal setting as claimed in claim 5 wherein said setting is made from substantially chromium free metal.

7. A method of manufacturing a drilled diamond die in a metal setting as claimed in claim 5 wherein said setting is made from an iron-nickel-cobalt alloy having about 28% of nickel and about 18% of cobalt.

8. A method of manufacturing a drilled diamond die in a metal setting as claimed in claim 5 wherein said setting is made from metal having about 70% of nickel and 30% of copper.

References Cited in the file of this patent UNITED STATES PATENTS 751,180 Krause Feb. 2, 1904 978,302 Joyce Dec. 13, 1910 1,008,442 Turnbull Nov. 14, 1911 2,212,394 Engle et al Aug. 20, 1940 2,239,425 Jacobson Apr. 22, 1941 2,328,794 Perrier Sept. 7, 1943 2,463,239 Bowman et al Mar. 1, 1949 2,481,071 Bowlus Sept. 6, 1949 2,694,951 OBrien Nov. 23,. 1954 2,778,250 Ploegsma Jan. 22, 1957 2,904,663 Emeis et a1 Sept. 15, 1959 

1. A METHOD OF MANUFACTURING A DRILLED DIAMOND DIE IN A METAL SETTING COMPRISING ARRANGING A DRILLED DIAMOND IN A GAS-TIGHT CHAMBER IN SAID SETTING, PROVIDING A NON-OXIDIZING GAS IN SAID CHAMBER, SAID CHAMBER HAVING LARGER INNER DIAMETER THAN THE OUTER DIAMETER OF SAID DIAMOND, PROVIDING A BORE IN SAID SETTLING OPENING CENTRALLY INTO SAID CHAMBER, SAID CHAMBER HAVING A CENTRAL APERTURE ADJACENT TO AND ALIGNED WITH ONE END OF SAID BORE, PROVIDING A METAL RING IN SAID CHAMBER SURROUNDING SAID DIAMOND AND HAVING A MELTING POINT LOWER THAN THE MELTING POINT OF SAID SETTLING, SAID METAL RING BEING CAPABLE OF WETTING SAID DIAMOND AND ADHERING TO SAID SETTING, THE MOLTEN AND SUBSEQUENTLY SOLIDIFIED METAL OF THE RING BEING LOCATED IN SAID CHAMBER, INTRODUCING THE SETTING INTO THE FIELD OF A CONCENTRATOR OF A HIGH FREQUENCY GENERATOR TO MELT SAID RING, AND DRILLING SAID METAL MASS AFTER SOLIDIFICATION THEREOF TO PROVIDE AN OPENING CORRESPONDING TO THE BORE OF SAID DIAMOND AND AT THE OTHER END OF SAID BORE. 